Safety device for high-speed elevators



Aug. 19, 1924.

M. A. BAKER ET AL SAFETY DEVICE FOR HIGH SPEED ELEVATORS 2 Sheets-Sheet1 Filed Sept. 24, 1923 O h T 4 5 Z W m 5 v w, z 4 8 M. O M

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M. A. BAKER ET AL SAFETY DEVICE FOR HIGH SPEED ELEVATORS Filed Sept. 24.1923 2 Sheets-Sheet 2 17 Fig. "w M H z J7 I 16 41 ,25 m z! I J9 ZPatented Aug. 19, 1924.

U NITED ST ATES PATEN T, oiuu(is :1

ivrrno A. nausea, HERBERT u. nuaanr, AND SAMUEL 1;. KING, or nosnnennns,

7 CALIFORNIA.

SAFETY *nnvrcn' 'ro ni HIGH srEnn ELEvAr'ons;

Application filed September 24, 1923. Serial No. 664,436. I

.To-mll whom it may camera:

Be it known that we, MILO A.. BAKER. HERBERT U. DURANT, and SAMUEL U.KING, citizens of the United States, residing at 25 Los Angeles, in thecounty of Los v Angeles and State of California, have invented a new anduseful Safety Device for High Speed Elevators, of which the following isa specification. k

This invention relates to safety devices of the type employed. on highspeed elevators for preventing falling of the elevator platform or cabin, event of the suspension cables breaking. y

An object of the invention is to effect gradual stoppage of the fallingelevator platform within a comparatively short distance without shock.

In safety devices of this type of prior construction, a relatively greatperiod of time elapses before engagement of the friction shoes with theelevator guides occurs, and,

consequently, the elevator platform'falls a considerable distance beforethe slowing, up

or braking action on the platform begins.

A further object of this invention is to begin frictional retardation ofthe falling elevator platform when the platform. has

dropped but a comparatively: short. distance and to then gradually and'more slowly increase the friction so as to bring the elevator t a fullstop very shortly thereafter.

A further object is to provide a device of this character ofcomparatively, simple construction so that there will be very littlelikelihood of it gettingout of order,

The. accompanying drawings illustrate the invention: I I y Figure 1 is abroken side elevation of-a safety device constructed in accordance withthe provisions of this invention, the same being shown attached to theelevator platform beams and the elevator guides being omitted in thisview. 7 I

Fig. 2 is an inverted plan section on line 2-42 of Figure 1, theelevator guides being shown in place. I v

Fig. 3 is an end View of Figure 2, omitting the guides. I Fig. 4 is anenlarged fragmental plan, partly in section, from the linejindicated by4.-4, Figure 1. j

-Fig. 5 is an end view of Figureii from the left thereof.

Fig. -6 is a plan view similar a ri id,

but showing less of the shoe-operating arms, and the drumshaft is turnedsufficiently to" disengage the clutch and cause the rollers to rideuponthewedge-sleeve. a

Fig. is a fragmental end 'ew of Figure ,6 from thelefttxhereof', theposition ofthe-wedge sleeve shown in Fig. 4." I 4 zF-ig 8 is a sectionalelevation on the line indicated'by 8+8, Figure 6. I

. A governor-controlled drum .isindicated at 11. The governor and cablethat serve to .set this drum into operation are not illustrated ordescribedfherein since their construction and operation are wellunderstood in, the-art relating to elevator safety devices. It sufficesto state that, the governor is adjusted so that if the elevator plat-,form "attains a dangerous speed in descend? .ing, as, for example, incase the suspension cables break, the governor operates to cause acable, not "shown, wound onthe drum 11 to" be held stationary and thusturn said drum in the direction of thetarrow a in Figure 1. a The drum11 is:mounted on a shaft 12. having screw-threads 13 at its oppositeends, the screw threads being the reverse of ,eachother, that :is tosay, those at one :end being left hand and those at the other "righthand. The bearings of the shaft 12 are indicated at 14 and are formed ina yoke 15 which is bolted to the under face of a pair of platform beams16. The foregoing described construction is well understoodin this art.I 1 i Means are provided to press shoe against one of the elevatorguides and, in this instance, said means-are operated com par-ativelyfast by turning of the shaft 12 less than one revolution in onedirection to engage the shoe with the guide and operated at aslow'errateby further turning of the shaft to more and more forcibly engage theguide.v These means may be variously constructed. and the invention inits broader phases is not limited to the particular means correspondingto that V illustrated: The construction of said means,

now to be described, is provided in duplicate at opposite ends of theshaft Y12 and,

consequently, it will be necessary to describe 'only'Ythat at one end;The screw threads 13 engage athreaded nut17 which provides f at one end.a female clutch member 118 Y lent, to the drum shaft so as to be turnedby said shaft. During the normal operation of the elevator the clutchmembers 18, 19'will be in'engagement as in Figure 4: so that turning ofthe drum will. rotate the nut. I

The nut 17 is free to turn in a wedgesleeve 21., said sleeve being heldagainst longitudinal movement relative to the nut by a suitable lockingpin 22, or its equivalent. The wedge sleeve 21 is provided withlongitudinally extending slots 23, the bottom walls 24 of said slotsbeing aslant toward the axis of the drum shaft in a direction leadingaway from the clutch members or,

in other words, toward a pair of rollers 25 which are sufficientlynarrow to enter the slots 23. The rollers 25 are rotatably mounted onshafts 26 which are supported,

respectively, in pivotally mounted levers 27. Each of the shafts 26projects sufliciently beyond the levers 27 to engage the hookshape ends28 of a coil spring or springs 29 which, consequently, tend to hold therollers 25 normally in contact with flattened or cam faces 30 ofthe nut17, these faces 30 being contiguous to the portion .31 upon which thewedge sleeve 21 is mounted.

The pivots for the arms 27 are indicated at33 and are mounted in amember 34: that is bolted to the underface of the beams 16.

Pivoted at 35' to the'levers 27 is the shoe or shoes previously referredto and these shoes are indicated at 36 and are arranged on oppositesides of one of the elevator guides 37 so thatiwhen the rollers 25 arethrust outwardly by the wedge sleeve 21, the shoes 36 will be caused tofrictionally engage the guide 37. The parts just described areproportioned so that frictional gripping of the guide by the shoes 36takes place when the rollers 25 have ridden off of the cam faces 30, asin Figure 6. Resuming the description of the means operating the shoes,the nut 17 is provided at its periphery with a pair of shoulders 38, 39,the shoulder 38 being, adapted to be brought into engagement with ashoulder 40, on the wedge sleeve 21 when the nut is turned in thedirection indicated by the arrow 7) in Figure 8, and the shoulder 39being adapted to engage a shoulder 41 on the wedge sleeve 21 when thenut is turned in adirection opposite to that indicated by the arrow 6,or in the direction of the arrow (1, Figure 1.

The invention above described operates, as follows:

Assuming that the parts are in the positions in which they are shown inFigures 1 and 50f the drawings and that the elevator suspension cableshave broken, permitting the elevator platform to drop at a dangerousspeed, the drum 11 will be caused to rotate in the direction of thearrow or because ofthe operation of the elevator governor at a speedhigher than that at which the safety device is to remain inactive, in amanner Well understood in this art, thus rotating the shaft 12 in thedirection of the arrow 0, Figures 5,7 and 8. This rotation of theshaftrotates the clutch 18, 19, thus rotating the nut and causing the rollers25 to ride off of the cam faces 30 onto the higher cam faces 32,operating the levers 27 to cause the shoes 36 to operate comparativelyfast to frictionally grip the elevator guide 37. This rotation of theclutch also causes the shoulder 39 to engage the shoulder 41. Thisoccurs in less than a quarter of a turn of the shaft 12, and causes thenut 17 to be held against further rotation and, in consequence, said nutis translated from the position shown in Fig. 4, to the left thusdisengaging the clutch members and causing the slanting slot walls 24 towedgedly move the rollers 25 away from each other and thusto graduallycontract the shoes 36 at a slower rate upon the elevator guide 37, untilthe friction between said shoes and guide becomes so great as to bringthe elevator to a stop. Thus, it will be seen that there are providedmeans to first effect relatively quick contraction of the shoes 36 uponthe guide 37 and thereafter relatively ,slow contraction of said shoesupon the guide. By these means the shoes are moved from position givingample clearance between them and the guide to a gripping position withina period of time in which the drum shaft makes less than one revolutionor, in this instance, only about one-quarterof a revolution. Thisenables a falling elevator to be gradually stopped within a distancethat is less than that between two floors of a building.

The guide-blocks, shown at 42, are of the usual type employed on theelevator platform for engaging the guides 37 and, therefore, need not bedescribed in detail herein.

It will be readily understood from the foregoing description that thenut 17 constitutes a membermounted for rotation and translation, thatthe cam face 30 operates upon rotation of said member, that the slantingface 21 constitutes a cam face for the nut operating upon translation ofsaid member, that the rollers 25 constitute one form of follower whichmay be otherwise constructed, and that the drum '11, shaft 12, screwthreads 13, clutch 18, 19 with the shoulders 39, 41 constitute meansoperable to alternately rotate and translate said member. I

We claim:

1. A safety device of the characterdescribed comprising a shaft, a shoe,and means operated comparatively fast by turning of the shaft less thanone revolution in one direction to press the shoe against an elevatorguide and operated at a slower rate by further turning of the shaft tomore and more forcibly engage the guide.

2. A safety device of the character described comprising a shaft havingscrew threads, a nut engaging the screw threads, means operated by theshaft to releasably engage and rotate the nut, means to hold the nutagainst rotation after it has been rotated through a certain number ofdegrees of circular measurement, a shoe, and means operated by therotation of the nut and thereafter by translation of the nut to move theshoe toward an elevator guide.

3. A, safety device of the character described comprising a membermounted for rotation and translation and provided with a rotativeoperated cam face and with a translation operated cam face, a shoe, afollower operatably connected with the shoe and successively engaged bythe respective cam faces, and means operable to alterna tively rotateand translate said member.

Signed at Los Angeles, Calif, this 17th day of September 1923.

MILO A. BAKER. HERBERT U DURANT. SAMUEL U. KING.

